It's what most people would say if they were going on a cruise:
Polish is not that pedantic about dokąd and if there's no ambiguity, you can replace it with gdzie.
Conversely, when I was learning Russian at school, the teacher emphasised that we shouldn't use где for direction. The translation of a perfectly proper Polish question "Gdzie idziesz?" to Russian isn't "Где идёшь?", as our 12-year old brains might have suspected, but "Куда ты идёшь?", literally "dokąd idziesz", which is also valid in Polish, but less common.
Does this sentence mean "sailing to" or does it mean "sailing". In english there is a different meaning to "where is this ship sailing" (where it is now) and "where is this ship sailing to" (where is it going to be). Now my answer (where is this ship sailing) got accepted, but the correct answers according to this section is "sailing to"
Yes, "łódź" is understood as a small vessel without a deck, with the exception of "łódź podwodna" - a submarine and "łódź żaglowa" = "żaglówka" = sail boat. It is usually a row boat or a small motor boat "łódź motorowa" = "motorówka". We also have larger vessels: medium to large size "statek" and a huge one "okręt".